Exar

Internally Switched Cable Termination on SP338 Enables RS-232 and RS-485/422 Protocols to Share Same Communication Lines

Fremont, California, January 10, 2012 - Exar Corporation (Nasdaq: EXAR) added another device to its versatile single-chip RS-232/RS-485/RS-422 serial transceiver product family today - the SP338. This device complements Exar's existing serial portfolio and further extends Exar's technology leadership in the single-chip multiprotocol market. The SP338 is ideal for industrial or embedded PCs with dual protocol serial ports. The RS-232 mode provides three drivers and five receivers to support all eight signals required for the DB9 serial port (3TX/5RX). The RS-485/422 modes include half, full, and mixed duplex configurations with up to two drivers and four receivers (2TX/4RX).

"The new SP338 and the recently announced SP339 solve the most difficult design issue of sharing a single connector between multiple serial protocols - enabling and disabling the termination resistor when switching protocols," said Jack Roan, technical marketing manager, Interface Product Line. "These devices provide multiple options for our customers to minimize the number of external connectors they use on their end-products, lowering part count and reducing overall system cost."

Product Features

The SP338 integrates the resistors and control switches for multiple RS-485/422 channels, allowing the system processor to dynamically enable or disable the termination with a single pin. The RS-485/422 modes include Exar's enhanced receiver failsafe on open, shorted, and terminated but idle inputs, eliminating the need for external resistor biasing networks and switching components.

When sharing a single connector between RS-232 and RS-485/422 protocols, the RS-485 termination and biasing resistors must be disconnected for proper RS-232 communication. Large and expensive relays are required to switch these resistors in and out of circuit due to the wide range of common mode voltage possible on a RS-485 network (anywhere from -7V to +12V). Most designers find it easier to have a separate external connector for each protocol, or to manually switch the resistor in and out, despite the additional size and cost of those approaches.

In addition to the on-chip switched cable terminations, the SP338 features eight configuration modes including diagnostic loopback, RS-232 (3TX/5RX), several half duplex RS-485 and full duplex RS-485/422 modes, as well as a mixed duplex mode with two drivers and four receivers (2TX/4RX). The maximum data rates of 20Mbps and 1Mbps (RS-485/422 and RS-232, respectively) can be slew limited to 256kbps in any mode by toggling a single control pin. The on-board charge pump generates the RS-232 bipolar voltage levels from a single 3.3V or 5V supply with only four external capacitors, and does not require any inductors or magnetic components.

All bus pins are protected against severe ESD events up to +/-15kV HBM (Human Body Model) and +/-8kV IEC 61000-4-2 Contact Discharge.

Interface Products

Exar has one of the broadest portfolios of high-performance interface solutions including RS-232, RS-485, and multi-protocol serial transceivers, UARTs, GPIO expanders, and integrated UART/transceiver combinations. For chip-to-chip or system-to-system connections, Exar's single and multi-channel interface ICs provides immediate competitive advantages to system architects: low power, reduction in board space requirements, increased bandwidth capacity, and enhanced product features. Interface devices are found practically everywhere including point-of-sale (POS) terminals, digital televisions, industrial automation equipment, handheld devices, and networking environments.

Prices, Packages, Availability and Additional Information

The SP338 is available now in volume quantities in a RoHS compliant 40-pin QFN package in Commercial (0 to +70ºC) and Industrial (-40 to +85ºC) operating temperature grades. Pricing starts at $5.58 per unit for 1K pieces. Additional information on this product can be found at: http://www.exar.com/interface/transceiver/multiprotocol/SP338/.

Exar's broad portfolio of transceiver solutions can be found at: http://www.exar.com/interface/transceiver/multiprotocol/.

1.8V to 6V Input Voltage Serves Low Voltage Core and RF Circuit Power Supplies

Fremont, California, December 13, 2011 - Exar Corporation (Nasdaq:EXAR) released today the XRP6272, a new low noise high performance LDO for up to 2 Amps point-of-loads.  Supporting a single 1.8V to 6V wide input voltage rail, the XRP6272 provides a 2 Amps point-of-load with an adjustable output voltage. It is equally capable of delivering power from as low as 0.7V for core voltage to a 5V for RF circuitry. Very low output noise combined with a high Power Supply Rejection Ratio (PSSR) makes it the ideal device for noise sensitive applications. The XRP6272's very low quiescent current provides enough versatility and performances to be used in portable equipment.

"The XRP6272 provides a unique point-of-load solution suitable for both low voltage core and 5V RF supplies," said Eric Pittana, director of marketing, Power Product Line. "It simplifies power management component selection to one single device for these architectures. The design flexibility of the XRP6272 will accelerate time-to-market for OEMs by reducing the complexity of their power designs. The XRP6272 joins an expansive family of market proven LDOs that are deployed successfully in varied applications and environments."

Key Product Features

Capable of a constant output current of up to 2 Amps, the XRP6272 supports a wide 1.8V to 6V input voltage range which allows for single supply operations from numerous industry standard power rails as well as the dedicated RF 5.8V rail. Better than +/-2% output voltage accuracy, low 24µVRMS output noise and 70dB PSRR make the XRP6272 perfectly suited for powering wireless RF circuitries. With an adjustable output voltage as low as 0.7V, this device is also capable of powering core processors and FPGAs. Allowing usage of small low cost ESR ceramic output capacitors and featuring a low 30µA quiescent current, the XRP6272 is optimized for use in battery powered portable equipments while an Enable function and Power Good flag complete the feature set. Built-in current limit and thermal protections provide the XRP6272 with fail-safe operations.

Power Management Products

Highly reliable, accurate, power management is a critical part of any technology system. Exar has a broad array of high-performance and industry-proven power management solutions including handset and lighting controls, power conversion, and standard linear devices.

Prices, Packages, Availability and Additional Information

The XRP6272 is available now in volume quantities and offered in a RoHS compliant, "green" halogen free 5-pin TO-252 package and 8-pin exposed pad HSOIC package. Pricing starts at $0.39 for 1K units.

Additional information on the XRP6272 product can be found at:
http://www.exar.com/power/power-conversion/ldos-and-regulators/linear-ldos/XRP6272/
Additional information on Exar's other LDOs and regulators can be found at:
http://www.exar.com/power/power-conversion/ldos-and-regulators/